Regulatory Effect of Fucoidan Hydrolysates on Lipopolysaccharide-Induced Inflammation and Intestinal Barrier Dysfunction in Caco-2 and RAW264.7 Cells Co-Cultures

Fucoidan, a sulfated polysaccharide rich in fucose, is derived from brown algae and marine invertebrates. Multiple bioactivities have been shown with fucoidan, while growing attraction has emerged in its low-molecular-weight (Mw) hydrolysates. Here, the anti-inflammatory effect of fucoidan, low-Mw acidolyzed fucoidan (LMAF, <1.5 kDa), and high-Mw acidolyzed fucoidan (HMAF, 1.5-20 kDa) were investigated in vitro using lipopolysaccharide (LPS)-stimulated Caco-2 and RAW264.7 co-cultures. Fucoidan, LMAF, and HMAF with different structures exhibited varied anti-inflammatory effects. LMAF and HMAF effectively decreased the nitric oxide release of RAW264.7 cells. LMAF exhibited a competitive effect in reducing tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 levels compared to HMAF and fucoidan. Transcriptome of RAW264.7 revealed that LPS and LMAF mainly regulated the transcriptional expression of genes, including <i>Tnf</i>, <i>Il6</i>, <i>Il1b</i>, <i>Junb</i>, and <i>Nfkb1</i> in the TNF signaling pathway, NF-kappa B signaling pathway, and cytokine-cytokine receptor interaction. RT-PCR results indicated that LMAF markedly reduced the LPS-elevated expression of <i>Cxcl2</i>, <i>Tnf</i>, <i>Ccl2</i>, <i>Il1b</i>, and <i>Csf2</i>. Moreover, LMAF effectively increased the proteins expression of Claudin-1, Occludin, and Zonula occluden-1 in Caco-2 cells. This study highlights the potential of LMAF to improve inflammation and intestinal barrier integrity, offering a foundation for further application of low-Mw fucoidan hydrolysates.